Arrangements of this kind are used in the prior art, for example, for monitoring glucose concentration in human blood. EP 0 722 288 relates to a method and a device for monitoring the concentration of a selected substance or a selected group of substances in a body fluid in the body of a living human or animal. The substance or group of substances to be monitored is conveyed out of the body through an interface and is transported away from the reverse side of the interface in a stream of perfusion liquid. The concentration of the substance or group of substances to be monitored is measured in the perfusion liquid downstream from the interface, the rate of flow of the stream of perfusion liquid being less than 60 μl/h.
DE 44 05 149 relates to an arrangement for determining the concentration of constituents in body fluids using a dialysis probe which can be implanted in body tissue and through which a perfusion solution flows, the inflow end of the dialysis probe being connected via a pump to a perfusion solution reservoir and the return flow end being connected to a collecting container via at least one enzyme cell serving as a sensor for the substance concentration. The enzyme cell output is connected to an extracorporeal evaluation/display unit. The perfusion solution reservoir, the pump, the enzyme cell and the collecting container are combined, separately from the evaluation/display unit, as a sensor unit in their own first housing. The dialysis probe, the perfusion solution reservoir, the pump, the enzyme cell and the collecting container are combined, separately from the evaluation/display unit, as a probe/sensor unit in their own second housing.
In such arrangements known in the prior art, a great many malfunctions can occur that have negative impacts on measurement accuracy. An incorrectly determined concentration value of the analyte can, however, have serious consequences for the person who is using the arrangement and who, for example, is controlling the administration of insulin as a function of the glucose concentration value that is determined. Consequently, reliable monitoring of the arrangement for determining the concentration of the analyte is necessary.